1. Field of the Invention
The present invention relates to a component-placing apparatus having a suction head for mounting an electronic component on a board or the like, or for assembling electronic components.
2. Description of the Related Art
Hitherto, a component-placing apparatus having a suction head has been used for mounting an electronic component such as a semiconductor chip and/or a piezoelectric component on a board such as a printed circuit board.
As an example of such a component-placing apparatus, as disclosed in Japanese Unexamined Patent Application Publication No. 5-82998, a nozzle head has been proposed in which a rotary motor for rotating a nozzle for applying suction to an electronic component and a cylindrical linear motor for vertically moving the nozzle, are disposed coaxially with the nozzle, such that moving parts of these motors rotate or move vertically while being integral with the nozzle.
Also, as disclosed in Japanese Unexamined Patent Application Publication No. 8-203966, a semiconductor-mounting apparatus has been proposed in which a suction nozzle, a pressure shaft which is movable vertically and rotatable and has the suction nozzle at the bottom thereof, an ultrasonic motor for turning the pressure shaft, and a voice coil motor for moving the pressure shaft in the vertical direction are disposed such that the pressure shaft extends through the voice coil motor and the ultrasonic motor.
In the former proposal, when the voice coil motor is used as the cylindrical linear motor, since the shaft extends through the center of the voice coil motor, the central part of the motor cannot be used as a core; hence, the voice coil motor does not effectively generate a thrust force. Accordingly, the size of the voice coil motor must unavoidably be large. Also, the rotary motor is rotated together with a yoke and a casing of the voice coil motor, thereby causing problems of large inertia and large size of the rotary motor. In addition, when a moving coil of the voice coil motor rotates together with the shaft, feeding the moving coil with current is difficult.
In the latter proposal, since the hollow pressure shaft extends through the center of the voice coil motor, the central part of the motor cannot be used as a core; hence the voice coil motor does not effectively generate a thrust force, thereby requiring the voice coil motor to be large. In addition, since a moving coil of the voice coil motor rotates together with the shaft, feeding the moving coil with current is difficult.